1. Technical Field
The present invention relates to a light source device having a pair of electrodes, a primary reflecting mirror, and a secondary reflecting mirror, and a projector using the light source.
2. Related Art
As a light source lamp used for projectors, for example, there is known a light source lamp having an auxiliary mirror in order for utilizing the light from an arc tube as efficiently as possible (see WO-2004-086451). In this case, as a result of using a secondary reflecting mirror such as an auxiliary mirror, there are some cases in which the temperature of the auxiliary mirror side electrode out of the pair of electrodes in the arc tube is raised, and accordingly, there is known a device of controlling the temperature by increasing the thermal capacity of the auxiliary side electrode (see WO-2004-086453).
However, in the light source using the auxiliary mirror, under the influence of the shape of the arc tube and so on, the reflected light by the secondary reflecting mirror do not necessarily enter between the pair of electrodes as intended. In this case, in particular, one of the pair of electrodes disposed on the side opposite to the auxiliary mirror might be irradiated with a part of the reflected light, which might become a factor for causing a damage on and deterioration of the electrode.
More specific explanations about this point will hereinafter be presented. In the light source device, the electrode on the anode side, which becomes the side of receiving electrons, is particularly damaged when the discharge between the pair of electrodes occurs. In this case, even if an equal alternating current is applied to the pair of electrodes, the influence of the irradiation by the reflected light from the auxiliary mirror is added with the damage by the discharge, and accordingly, the electrode more significantly influenced by the reflected light might be more seriously damaged and early deterioration might be incurred.